I've been in #TeamMasks since Day 1, but even I have to scratch my head at masks while sitting on a pool chair. They can distance groups by having the chairs at least 6 feet from the next party and it's all outdoors. These are conditions that are associated with less chance of spread. It's not like at a theme park where it's basically impossible to always be at least 6 feet away from every other party.
That is if people keep the chairs spread out but we all know what will happen. People are going to push the pool chairs close to each other. I've seen it at my local bar that has reduced bar stools to about 1/3. They have to come around all the time spreading them back out.